Method of operating a pressurized storage system



E. E. REED Sept. 13, 1960 METHOD OF OPERATING A PRESSURIZED STORAGESYSTEM 4 Sheets-Sheet 1 Original Filed April 13, 1953 Sept. 13, 1960 E.E. REED 2,952,135 METHOD OF OPERATING A FRESSURIZED STORAGE SYSTEMOriginal Filed April 15, 1953 4 Sheets-Sheet 2 FIG. 3

E. E. REED Sept. 13,.1960

METHOD OF OPERATING A PRESSURIZED STORAGE SYSTEM Original Filed April15, 1953 4 Sheets-Sheet 3 INVENTOR. E.E.REED

E. E. REED 4 Sheets-Sheet 4 FIG. 9

INVENTOR. EvE.REED

Sept. 13, 1960 METHOD OF OPERATING A PRESSURIZED STORAGE SYSTEM OriginalFiled April 15, 1953 2 3 2 m n m 4 5 2 9 r (\M 7/ Whfi'lr J- F V I p v V2 7 8 3 2 2 9 B I H United States Patent O METHOD OF OPERATING APRESSURIZED STORAGE SYSTEM Edwin E. Reed, Bartlesville, Okla., assignorto Phillips Petroleum Company, a corporation of Delaware Originalapplication Apr. 13, 1953, Ser. No. 348,344, now Patent No. 2,901,889,dated Sept. 1, 1959. Divided and this application Jan. 26, 1959, Ser.No. 788,846

6 "Claims. (Cl. 62-45) This invention relates to an improved method ofoperating a pressurized storage system. In one of its aspects thisinvention relates to a method of inserting and withdrawing a pump from apressurized container without loss of vapors from high vapor pressureproducts stored therein.

This application is a division of my copending application Serial No.348,344, filed April 13, 1953, now US. Patent 2,901,889, issuedSeptember 1, 1959.

This invention is directed in part to the storage and removal fromstorage of liquefied gases and in a preferred modification is directedto the underground storage of liquefied petroleum gas. The constantlyexpanding production of liquefied petroleum gas has created a definiteproblem in providing suitable storage facilities for this material. Dueto the high pressure of liquefied petroleum gas, particularly propane,the cost of storage in surface equipment, such as steel tanks, becomesexcessive due to the massive construction required to withstand thevapor pressure in a safe manner. This problem becomes extremely acutewhere it is necessary to store large quantities of such material duringthe QE season.

In order to overcome some of the difficulties, it has been proposed tostore liquefied petroleum gas in porous water bearing formations, inwater-leached caverns in salt formations or in abandoned mines inimpermeable shale or in limestone formations. Further, undergroundconcrete storage tanks and buried sections of pipe have been used to alimited extent in the storage of liquefied petroleum gas.

In accordance with a preferred embodiment of this invention, anunderground storage system for liquefied petroleum gas is provided whichis capable of storing extremely large quantities of this material at avery small unit cost. Further, a number of operating and safety featuresare provided to insure a long period of troublefree operation of thestorage system, together with easy and reliable introduction of thematerial into storage and removal of material therefrom. The storagesystem is not limited to storage of liquefied petroleum gas, but isapplicable to the storage of any liquefiable gas such as ammonia, carbondioxide, and the like. Further, the present invention is not necessarilylimited to underground storage systems and can be employed where steeltanks are used as the pressurized storage container.

There are many methods of removing liquefied gas from a storagecontainer. For example, it is well known that a liquefied gas can beforced from a chamber by introducing compressed gas above the liquid. Inother instances, displacement by a second non-contaminating liquid ofgreater density can be employed. One method, and a more generallypreferred method, for removing a liquefied gas from storage is by meansof a centrifugal pump. The pump is usually contained within thepressurized container and can be one wherein the motor driving the pumpis also submerged, or of the type driven by a rotating shaft attached toa motor on the outside ofthe container. It is recognized that such pumpswill have to be pulled from the container from time to time for repairor replacement. To do this, some means must be provided to prevent theloss of large quantities of vapor from the container. In order that thecontainer can be tightly sealed during the time the pump is beingoperated or being inserted or withdrawn, I have devised a system andmethod which will be described in terms of one preferred modification,namely the storage in underground chambers of liquefied petroleum gas.

'It is an object of this invention to provide an improved method ofoperating a pressurized storage system.

A further object of this invention is to provide a method forintroducing and withdrawing a pump from a pressurized storage containerwithout loss of vapors from high pressure products stored therein.

Various other objects, advantages and features of the invention willbecome apparent from the following detailed description taken inconjunction with the accompanying drawing, in which:

Figure 1 is a vertical sectional view, partly in elevation, of part ofan underground storage system constructed in accordance with thisinvention;

Figure 2 is an enlarged vertical sectional view, partially in elevation,of the top portion of the shaft of Figure 1;

Figure 3 is an enlarged vertical sectional view, partially in elevation,of a casing head;

Figure 4 is an enlarged vertical sectional view, partially in elevation,of a tubing head and a slip joint for a submerged pump driven by meansof a shaft extending to a motor at the surface;

Figure 5 is a vertical sectional view, partially in elevation, of a pumpand downhole valve unit;

Figure 6 is a sectional view taken along the line 6-6 of Figure 5,looking in the direction of the arrows;

Figure 7 is an enlarged vertical sectional view, partially in elevation,of a tubing head and slip joint for a submerged pump actuated byelectrical means extending from the surface to the motor unit, alsosubmerged;

Figure 8 is a sectional view taken along the line 88 of Figure 7 lookingin the direction of the arrows; and

Figure 9 is a vertical sectional view of the modified form of tubinghead and casing head.

Referring now to Figure l of the drawing in detail,'

an underground storage system in which I prefer to practice my inventionincludes at least one storage cavern which contains at least one chamber10. The caverns can be constructed in a variety of different ways asillustrated in the copending application of Leonard P. Meade, Serial No.314,541, filed October :1-3, 1952, now abandoned, which copendingapplication also discloses a preferred modification of the presentinvention. For example, a single large cave can be excavated, or anumber of smaller caves can be formed and interconnected in any suitablemanner. As shown large chamber 10 communicates by means of tunnels 11and 12 with an enlarged vertical shaft 13 extending from the surface ofthe earth to a region adjacent the cavern. Other caverns in the systemare not shown in the drawing. The storage chambers can be of anygeometric shape.

Disposed in each tunnel 11 is a drain pipe or header 14, and the headersof all the caverns extend through the respective tunnels and communicatewith the shaft 13. Each storage chamber is provided with a drain pipe 15which at its lower end is connected to the header 14 and which extendsupwardly into the associated storage chamber 10. Thus, should the tunnel11 become choked with rock or dirt due, for example, to caving, the mainstorage portion of the chamber still communicates with the shaft throughits associated pipe 15 and header 14. As a result, should caving occurwhile fluid is stored within the chamber the fluid can drain out throughthe described pipe and header, and the main storage portion of thechamber is available for further service even when caving occurs.

Although such drain pipes are very advantageous in many installations,they may not be required in cases where the formation is not subject tocaving.

Forming a part of each cavern is an upper tunnel 12, each upper tunnelbeing connected to one of the storage chambers and communicating withshaft 13. Disposed in each tunnel 12 are a pair of vent pipes 16 and 17communicating with shaft 13. and theadjacent chamber 10. The purpose ofthese vent pipes is to provide venting of the entire underground storagesystem to equalize pressure throughout. It will be evident that, ifdesired, tunnel sections 12 can be eliminated and the describedcommunication between the upper part of the storage chambers and theshaft can be eflected solely by the vent pipes 16 and 17. Conversely,the vent pipes 16 and 17 could be eliminated and venting effectedthrough the tunnel. Where diflerent types of caverns are used anysuitable means can be employed to equalize the vapor pressure above theliquid to be stored in the various caverns or storage chambers of thesystem. One or more of the caverns is provided with a drilled hole 18extending from the surface of the earth to the top of the associatedcavern through which material is introduced into the system for storage.The filling mechanism at the surface, not shown, is of a nature toprevent loss of pressure from the system. Suitable mechanism isillustrated in the aforementioned copending application of Leonard P.Meade, Serial No- 314,541.

The shaft 13 incorporates pump mechanisms to be hereinafter described indetail for lifting the stored fluid from the bottom of the shaft to thesurface from whence it is passed to transportation and marketingoutlets, or

other desired use. In operation, therefore, the material to be stored isintroduced into the top region of the caverns by filling means 18, orsuch filling means or pipe can extend to the bottom of the cavern.Material withdrawn from storage flows through the lower tunnel '11 and/or the header 14 to the shaft 13 where it is lifted to the surface foruse as described. Materials such as liquefied petroleum gas have a highvapor pressure and the thickness of the earth layer above the caverns iseffective in containing this high vapor pressure without the use ofsteel tanks or a lining for the cavern. In one specific embodiment ofthe invention, the storage chambers are formed in an impermeable shaleformation, whereby a long period of trouble-free operation is assured.

Referring again to Figure 1, two strings 20 and 21 of casing extend fromthe surface of the earth through means hereinafter described and thelower portion of shaft 13 into a well 22 formed at the bottom of theshaft. It will be noted that the well 22 is below the level of thetunnels 11 and caverns so that fluid can flow from each one of thestorage chambers into'the well. At the bottom of the well, the casingstrings 20 and 21 are received within enlarged sections 23 and 24,respectively, of pipe which are anchored in a mass 25 of cement at thebottom of the well. Disposed at the lower ends of casing strings 20 and21 are valves 26 and 27 respectively, and immediately above these valvesare pumping units 28 and 33. Pump 28 is a multiple stage pump supportedwithin casing 20 by means of tubing 30 and driven by rod 31 extendingthrough tubing 30 to the surface. Pump 33 is supported within casing 21by means of tubing 32 and incorporates a motor 29 which is actuated by asuitable electrical current source at the surface. Both pumps areactuatable to lift the fluid stored within the system through the shaftto the surface.

Referring now to Figure 2 of the drawing, it will be noted that anenlarged tubular metal liner 40 formed, for example, from steel isprovided at the top of the shaft and this liner is anchored by a mass 41of cement disposed above the exterior of the liner. The liner extends asubstantial distance downward in the shaft, if desired,

purpose of supporting the walls of the shaft and substantially orcompletely eliminating the flow of water or other liquids into theshaft. The liner, of course, also prevents the escape of the storedmaterial. The mass of cement includes an enlarged rounded upper section'42 adjacent the surface of the earth and supporting and anchoring theliner 40, a generally cylindrical portion 43 surrounding the body of theliner 40, and a lower inwardly protruding portion 44 adjacent the bottomof the liner. The top of the liner protrudes a short distance above theearth and is closed by an enlarged flat plate or well head 45. It willbe evident that the liner 40, well head 45 and mass 411 of cementconstitute collec tively means for sealing the shaft 13 at a regionabove the level of the lower tunnels 11 and upper tunnels 12. A manholeclosed by a cover 46 is provided in the liner for access into thestorage system for any desired purpose.

With respect to pump 28, it will be noted that the easing string, tubingstring, and drive rod all extend upwardly through the shaft 13, theliner 40, and the well head to the surface, where these parts all passthrough a valve 50, Figure 2, on top of the well head. Immediately abovevalve 50 is a head 51 from which the casing string is hung. Referring toFigure 3, it will be noted that the casing head includes a generallycylindrical body 52 bolted to an adjacent flange of valve 50 andprovided with valved connections 53 and 54. The upper end of casingstring '20 is threaded to a tapered annular block 55 which engages acomplementary tapered surface 56 of the body 52, the block beingprovided with a plurality of sealing gaskets 57 and held in position bybolts 58. The gaskets 57 seal the region between the body 52 and easingstring 20, this region communicating through valve 50 with the topportion of shaft 13. A pipe 60 is threaded to the top of block 55, thispipe extendingupwardly to and supporting a valve 61, Figure 2.

The tubing string 30 with its concentric drive rod 31 extends throughpipe 60 and valve 61 to a combination tubing head and slip joint 62, thedetailed construction of which is shown by Figure 4.

Referring to Figure 4, it will be noted that the tubing head includes agenerally cylindrical body 63, the lower end of which rests upon and issupported by an adjacent flange 137 of valve 61. The upper end of thetubing 30 is threaded to a flanged block 64 which is bolted to a flange65 secured to the body 63. An annular member 66 fits between the body 63and the tubing 30, this member being provided with an annular sealinggasket 67. Secured to the flange block 64 is a pipe communicating withthe interior of the tubing and provided with an outlet conduit 71.Immediately above this conduit is a sealing member 72 through whichextends drive rod 31 of the pump, this rod being driven by an electricmotor 73, Figure 2, at the top of the assembly.

In assembling and operating the apparatus, valve 50 is opened and thecasing string is hung from casing head 51 so that it extends downwardlythrough valve 50 to its position within the pipe 23, Figure 1. Attachedto the lower end of the casing is the valve 26 which is normally closedso that, once the casing is inserted and the casing head sealed, nomaterial can pass through casing to the surface nor between the casingand the body 52. Thereupon, the tubing string and drive rod are loweredinto the well section by section, it being understood that the pump 28is secured to the lowermost section of tubing. This process continuesuntil the pump is disposed a short distance above the valve 26, at whichtime the annular member 66, Figure 4, and sealing gasket 67 arepositioned at the upper end of the cylindrical body section containingthem, and the flanged block 64 with its attached pipe 70 is positioned ashort distance above the cooperating flanged member 65. At this time,the interior of the casing ispressurized as by connecting valves 53 and91, similarly as valves 53a and 91a are connected by conduit 138 inFigure 2, that is, the pressure in the casing is equalized with thepressure in the underground storage system. Thereupon, the tubing islowered to its final position, thereby causing the pump body to engagethe valve 26 and open it. Due to the annular member 66 and sealinggasket '67, the vapor in the casing cannot escape during the period whenthe tubing and pump are lowered into the final operating position, atwhich time the flanged block 64 is bolted to the part 65 and the systemis sealed.

Thereafter, when the motor 73 is energized, the resulting rotation ofrod 31 and pump 28 lifts fluid to the surface of the storage chamber.

Referring to Figures 1, 5 and 6, it will be noted that fluid passes intothe pipe 23 from the tunnels 11 and headers 14 leading to the storagechambers. From the bottom of the pipe 23 fluid enters a lower section80, Figure 5, of the valve 26, this valve section being centered by aseries of vanes 81 protruding from the wall of the pipe 23. The valve 26further includes a valve head 82 engageable with a valve seat 83 in anupper section 84 of the valve. The valve head is mounted upon a stem 85which passes through a spider 86 and cooperates with a spring 87 urgingthe valve towards closed position. When the pump is positioned above thevalve, as indicated by solid lines in Figure 5, the valve is closed bythe action of spring 87 and no fluid can enter the casing from the lowersection 80 of the valve. However, when the pump is lowered into itsoperating position, as indicated by the dotted lines in Figure 5, thevalve stem 85 is displaced by the pump body and the valve is opened,thereby allowing the fluid to pass through the valve to the pump intakein the casing. The pump, thereupon, lifts the fluid through the tubing,the surface structure 50, 61, and 62, Figure 2, and to and out throughdischarge conduit 71, Figure 4.

Should it be necessary to remove the pump for servicing, the flangedblock 64, Figure 4,is detached from flange 65, and the tubing 30 islifted a short distance so that the pump body, Figure 5, moves out ofengagement with valve stem 85 and closes the valve, thereby sealing thelower end of the casing. Any fluid pressure existing in the casing canthen be removed or bled by venting the interior of the casing to theatmosphere, it being understood that the interspace between the tubingand the casing is sealed by annular ring 66, Figure 4, and gasket 67,while the tubing is being raised a suflicient distance as to allow thevalve to close. It will be noted that pipe 60 is provided with apressure gage assembly 90, Figure 2, and a valved pipe 91, the describedbleeding being effected by a hose 139 from valve 91 to a suitable remotevent pipe, not shown. After the pressure has been vented, the tubingsection and the drive rod section can be readily lifted and removed withresultant lifting of the pump 28 out of the shaft. When the removal iscompleted, valve 61 can be closed to provide a positive sealimplementing the seal produced by the downhole valve 26, Figure 5. Aline 92, Figure 2, which extends from an opening 93 in pipe 60communicating with the casing to the seal assembly 72 allows liquid fromthe seal to drain back into the system.

Many features of construction of the pump unit and easing string 21 aresimilar to those described in connection with the pump unit and casingstring 20. In this construction, the motor 29, Figure 1, is downhole,and is mechanically connected to pump 33. The casing string 21 and thetubing string 32 supporting the pump-motor assembly extend upwardlythrough the shaft 13, the liner 40, and the well head 45 through a valve50a, a casing head 51a, a pipe 60a, and a valve 61a corresponding instructure and function to the similarly numbered parts described inconnection with the casing string 20. Positioned above valve 61a is atubing head and slip joint 62a which is similar to tubing head 62 butwhich is 6 modified as will hereinafter be described to provide forelectrical leads which supply power to motor 29.

Electric power is supplied to motor 29 by said leads 95 from a suitablesource of current, not shown, said leads extending upwardly through theinterspace between casing 21, Figure 1, and tubing 32 and thence throughpipe 60a and tubing head 62a to the surface. The downhole valve 27 issimilar in construction and operation to the Valve 26 so that the casingstring and tubing string can be inserted into or removed from the shaft13 in the manner described in connection with the tubing '30 and casing20. When the pump is energized by application of a suitable electriccurrent to electric motor 29, fluid flowing from the storage chamberthrough tunnel 11 or header 14 passes downwardly through pipe 24 and,then, upwardly through valve 27, the pump unit and the tubing 32 to thesurface, whence it is removed through outlet conduit 71a.

Refening to Figures 7 and 8, tubing head 62a is modified to provide forelectrical leads 95 which pass to motor 29 through the annular spacebetween tubing 32 and casing 21. The seal is maintained by means of anannular member and a gasket 101. However, to provide for the passage ofleads 95 through annular member 100, said member is split along the line102, Figure 8, and lead 95 is held tightly in place by screws 103. Itwill be noted that the steel sheathing covering the insulation may bestripped from the electrical leads 95 from a point below annular member100 and above the outlet of said leads from tubing head 62a throughflange 64a. If desired, a short length of pipe can be secured to flange64a, this pipe being concentric with and surrounding tubing '32. Thecable can then pass between pipe 32 and this additional length of pipeso that there is no necessity of it passing through member 100.

Electrical leads 95 leave tubing head 62a through hole in flange 6411. Aseal is maintained around said leads 95 by means of a gasket 111, heldin place by means of plate 112 and screws 113. It will be appreciatedthat the removal of leads 95 from annular member 100 and from flange 64amay be facilitated by providing said leads 95 with suitable socketconnections which can be easily engaged and disengaged.

An alternative and preferred construction for the motor-pump unit 29 isshown in Figure 9. In this figure, casing string 24 terminates, at theupper end thereof, in an upper section 118 which is flanged to a member119 of similar construction to the member 63 of Figure 4, the flangedconnection being denoted by reference numeral 120. Fitting within themember 119 is a short piece of pipe 121 carrying a flange 122 which isbolted to a flange 123 at the top of member 119. The lower end of pipe121 carries an annular member 125 fitting between the pipe 121 and themember 119, the annular member 125 being provided with an annularsealing gasket 126. At the upper end of pipe 121 is threaded a tubinghead 127 incorporating slips 128 supporting the tubing string 32.

Slips 128 are constructed and arranged to define a passage 129 for thecable 95. A rubber packing ring 130 is mounted above the slips 128, thispacking ring being provided with openings for the passage of tubingstring 32 and cable 95, and being compressible by a cap 131 engageableby a pressure member 132 bolted to a flange 133 at the top of the tubinghead 127. At the uppermost portion thereof, the tubing string 32 isprovided with a T-section 134, one portion of the T having a valve 135secured thereto and the other portion 136 of the T leading to a suitableoutlet for the stored fluid.

When it is desired to remove the pump for servicing, flange 122, 123 canbe unbolted and the tubing string together with tubing head 127 and pipe121 lifted a short distance so as to close downhole valve 127, Figure 1,without breaking the seal at annular member 126. When the downhole valveis closed, the fluid can be bled from the interspace between the tubingand casing, after which the casing and pump can be lifted out section bysection until it reaches the surface. The advantage of the constructionof Figure 9 is that the initial lifting of the tubing does not cause thetubing to move upwardly through the packing ring 130 which might resultin damage to the packing ring from the frictional engagement of thetubing therewith. After the downhole valve has been closed, the tubinghead can, of course be readily disassembled without injury to thepacking ring and without the escape of fluid from the undergroundstorage system. Similarly, upon replacing the pump, annular member 126seals the casing as the tubing string and pump are lowered intoengagement with the downhole valve for resumption of operation of thestorage system.

In its broadest aspect, this invention is directed to a method forwithdrawing a pump from a pressurized container without loss of pressuretherein, said container being provided with a conduit extending througha boundary of said container and closably communicating with saidcontainer, said pump being positioned within said conduit adjacent theregion of communication of said conduit with said container, bypartially withdrawing said pump from said conduit and therebyconcomitantly closing off said conduit from said container, releasingthe pressure within said conduit, and thereafter completely withdrawingsaid pump from said conduit.

While this invention has been described and exemplified in terms of itspreferred embodiment, those skilled in the art will appreciate thatmodifications may be made without departing from the spirit and scope ofsaid invention.

I claim:

1. A method for withdrawing a pump from a pressurized container withoutloss of pressure therein, said container being provided with a conduitextending through a boundary of said container and closablycommunicating with said container, said pump being positioned withinsaid conduit adjacent the region of communication of said conduit withsaid container, which comprises, partially withdrawing said pump fromsaid, conduit and concomitantly closing off said conduit from saidcontainer, releasing the pressure within said conduit, and thereaftercompletely withdrawing said pump from said conduit.

2. A method of inserting into and withdrawing a pump from a pressurizedcontainer without loss of pressure therein, said container beingprovided with a conduit extending through a boundary of said containerand closely communicating therewith, which comprises, inserting saidpump into said conduit in a manner preventing communication of saidconduit with said container, pressurizing said conduit to an extentapproximating that in said container, positioning said pump in saidconduit to provide communication between sad conduit and said container,operating said pump until it is desired to remove same, partiallywithdrawing said pump from said conduit and concomitantly closing offsaid conduit from said container, releasing the pressure within saidconduit, and thereafter completely withdrawing said'pump from saidconduit.

3. A method for withdrawing a pump from a pressurized container withoutloss of pressure therein, said container being provided with a volumeextending through a boundary of said container and closablycommunicating with said container, said pump being positioned withinsaid volume adjacent the region of communication of said volume withsaid container, which comprises partially withdrawing said pump fromsaid volume and concomitantly closing oft said volume from saidcontainer, releasing the pressure Within said volume, and thereaftercompletely withdrawing said pump from said volume.

4. A method for inserting into and withdrawing a pump from a pressurizedcontainer without loss of pressure therein, said container beingprovided with a volume extending through a boundary of said containerand closably communicating with said container, which comprises,inserting said pump into said volume in a manner preventingcommunication of said volume with said container, pressurizing samevolume to a degree approximating that in said container, positioningsaid pump in said volume to provide communication between said volumeand said container, partially withdrawing said pump and concomitantlyclosing off said volume from said container, releasing the pressure insaid volume, and thereafter completely withdrawing said pump from saidvolume.

5. A method for withdrawing a pump from a pressurized undergroundstorage system without loss of pressure therein, said system beingprovided with a conduit extending from the surface of the earth into aregion near the bottom of said system, said pump being positioned withinsaid conduit adjacent the region of communication of said conduit withsaid system, which comprises, partially withdrawing said pump from saidconduit and concomitantly closing ofi? said conduit from said system,releasing the pressure within said conduit, and thereafter completelywithdrawing said pump from said conduit.

6. A method of inserting into and withdrawing a pump from a pressurizedunderground storage system without loss of pressure therein, said systembeing provided with a conduit extending from the surface of the earth toa region near the bottom of said system, said conduit closablycommunicating with said system, which comprises, inserting said pumpinto said conduit in a manner preventing communication of said conduitwith said system, pressurizing said conduit to approximately thepressure in said system, positioning said pump in said conduit toprovide communication between said conduit and said system, operatingsaid pump until it is desired to remove same, partially withdrawing saidpump from said conduit and concomitantly closing off said conduit fromsaid system, releasing the pressure within said conduit, and thereaftercompletely withdrawing said pump from said conduit.

References Cited in the file of this patent UNITED STATES PATENTS2,230,830 Coberly Feb. 4, 1941 2,280,087 Hollander et al. Apr. 21, 19422,297,185 Hollander et al. Sept. 29, 1942 2,780,070 Meade Feb. 5, 19572,883,833 Miles Apr. 28, 1959 2,901,889 Reed Sept. 1, 1959

